There are some pretty good resources and tutorials on the main Eclipse and IBM’s site. One of the best ways is to pick an open source plug-in that has some similar features to what you want to do and start to dissect it.
- PDE Does Plug-ins
- Plug-in development 101, Part 1: The fundamentals
- Eclipse Plugins Exposed, Part 1: A First Glimpse
- Developing Eclipse plug-ins